Strand treatment



March 26, 1968 c. A. MccLURE 3,374,514

STRAND TREATMENT Filed April 20, 1966 I/VVE/VTOK. CHARLES A. McCLUREUnited States Patent 3,374,514 STRAND TREATMENT Charles A. McClure, RJ).2, Malvem, Pa. 19355 Filed Apr. 20, 1966, Ser. No. 543,957 8 Claims.(Cl. 28-72) ABSTRACT OF THE DISCLOSURE This invention relates totreatment of textile strands, concerning especially strand-crimping. Aprocess is provided for directing hot fluid obliquely onto one side of atextile strand, the opposite side of which is maintained relativelycool. The strand so treated subsequently assumes a crimped configurationupon being forwarded away from the treating location.

In addition to edge-crimping, gear-crimping, jet-crimp ing,stutter-crimping, and twist-crimping it is known to crimp textilestrands of at least partially oriented (molecularly) linear polymericmaterial by setting up a temperature gradient transversely of thestrand, whereupon the strand assumes a helically cn'mped configurationunder low (or no) tension after cooling of the heated side. In the lastmentioned method the heating of the one side of the strand may beaccomplished by contact with a hot solid, liquid, or gas; the oppositeside is maintained cool by conductive contact with a solid surface atappropriate temperature. Resulting processing and productcharacteristics leave a good deal to be desired, however.

A primary object of the present invention is improved transversetemperature-gradient treatment of textile strands.

Another object is in textile strands.

A further object is provision of apparatus for accomplishing theforegoing objects.

Other objects of this invention together with means and methods forattaining the variousobjects, will be apparent from the followingdescription and the accompanying diagrams.

FIG. 1 is a side elevation, partially schematic, of ap paratus accordingto the present invention; and

FIG. 2 is a side elevation, on an enlarged scale, of a detailed portionof FIG. 1.

FIG. 3 is a front elevation of a roll component of the preceding views;and

FIG. 4 is oblique sectional view taken at IVIV on FIG. 2.

In general, the objects of the present invention are accomplished intreatment of a textile strand wherein the strand is heated on one sideand maintained relatively cool on the opposite side, by subjecting thestrand on that provision of improved helical crimp first side during theheating thereof to a stream of hot fluid incident onto the strand at anoblique angle and having a velocity component in the running directiongreater than the strand velocity.

More particularly the invention comprehends a strandcrimping processcomprising forwarding a plasticizable molecularly oriented textilestrand of linear polymeric material into a treating zone, heating thestrand on one side only to its plasticization temperature by directingthereonto a stream of hot fluid having a velocity component in theforwarding direction, maintaining the opposite side of the strand coolerthan the plasticization temperature, and cooling the strandsubstantially tensionfree, whereupon it assumes a crirnpedconfiguration.

FIG. 1 shows, in side elevation and partly schematically, strand beingwithdrawn from supply package 11 by pair of nip rolls 13, 14 from whichit passes at least a I let opening denote the flow of hot fluidtherefrom which.

3,374,514 Patented Mar. 26, 1968 half turn about flanged cool roll 15,to the recessed peripheral surface of which is juxtaposed jet end 21 ofpipe 22 for hot fluid supplied from source 24 through valve 23 in thepipe. From the cool roll the strand is withdrawn and is forwarded aboutpart of the roll 17, which is driven or not driven as desired, then pastheater 18, and is traversed onto windup package 20 driven by surfacecontact with traversing drive roll 19. The cool roll rotates on axle 16(shown sectioned).

FIG. 2 shows, also in side elevation but partly in section andconsiderably enlarged, a portion of cool roll 15 and adjacent elements.Part of near flange 25 of the roll is broken away, revealing theotherwise concealed corresponding portion of opposite flange 25 as wellas jet end 21 and the adjacent length increment of strand 10. Therollhas hollow 28 inside, which is supplied conventionally with coolingfluid (not shown). Jet end 21 is concave in the plane of the view, injuxtaposition to the recessed arcuate peripheral surface of the roll,with sufficient clearance for strand 10 to pass therebetween. The jetoutlet is aligned with bore 27 in pipe 22, and the emitted hot fluid(not shown) is incident at an oblique angle onto the exposed side of thestrand, which runs about the roll in essentially non-slipping surfaceWith that recessed peripheral surface thereof. The supply pressure ofthe hot fluid is such that the velocity com-,

ponent thereof in the direction of strand travel exceeds the rate oftravel of the strand.

FIG. 3 shows, in front elevation on the same scale as in FIG. 2, aportion of cool roll 15, without strand 10 on recessed peripheralsurface 26 thereof, which is flanked by pair of flanges 25, 25'. Thisview is what would be seen upon looking leftward from a position to theright of cool roll 15 in the preceding views before the strand is strungthereon.

FIG. 4 shows, also in front elevation and partly in section, theelements visible looking obliquely leftward at lV1V in FIG. 2. Jet end21 with outlet opening 29 therein is visible end-on, with part of pipe22, and flanked by part of flanges 25, 25 (shown sectioned) of cool roll15, which is not otherwise visible. Arrows from the outis predominantlyupward in this view, corresponding to movement in the running directionof the strand rather than otherwise. The roll flanges serve to channelthe flow parallel to that direction instead of permitting it to bedissipated in any great part by a transverse velocity component.

The temperature of the hot fluid should be sufliciently above theplasticization temperature of the strand com position to soften theexposed side of the strand in the relatively brief time it is exposedthereto. For nylon the fluid temperature preferably is at least about acouple hundred degrees Centigrade. The cool roll should be maintainedwell below the strand composition plasticization temperature, preferablynot more than about twice room temperature in degrees Centigrade.

As the hot fluid impinges onto the exposed side of the strand, softeningthereof occurs. Because the velocity component of the fluid in therunning direction of the strand is greater than the strand velocity,preferably from several to about ten times as great, the softened sideof the strand is subject to being extended thereby in the direction oftravel relative to the opposite side, which strand. More than one strandmay be treated side by side on the same roll if desired, especiallyWhere the strands are monofilaments or contain few filaments apiece.

Strands may be treated according to this invention either under tensionor essentially tension-free. In the first instance the rate of strandwithdrawal from the package, as by nip rolls 13, 14 or the equivalent,is maintained sufliciently lower than the surface speed of cool roll 15to impart the desired degree of tension to the strand therebetween, androll 17 is preferably driven at the same surface speed; the windup rateis lower to enable the strand to relax at least partially before beingwound up. In the second instance the surface speed of nip rolls 13, 14may be the same as that of cool roll 15, and roll 17 may be undriven. Inboth instances the cool side of the strand passes in essentiallynon-slipping contact with the peripheral surface of the cool roll.

Although only imperfectly understood, the resulting helical crimp in thetemporarily tensioned strand may be at least partly attributable to aheat-induced molecular disorientation of the exposed side of the strandsuch as to preclude subsequent recovery thereof from the increasedlength imparted thereto by the previously applied tension, whereas theopposite side, which retained its molecular orientation and consequentelasticity, retracts to become relatively shorter. The difference inlength along the respective sides forms the strand into helicalconfiguration.

When a strand is treated in essentially tension-free condition thesimilar result is probably not attributable to'the same phenomenon ofdifferential retraction from applied tension, although a strandconsidered essentially tension-free may have internal strains capable ofproviding a similar though lesser effect under the treating conditions.Instead it appears that a principal influence is relative lengthening ofthe softened exposed side of the strand, as the hot fluid impingesthereon with a velocity component in the direction of strand travel,without imparting molecular orientation thereto such as usually resultsupon extension of a strand composed of linear polymeric material. Theresulting difference in relative lengths of the respective oppositesides of the strand, apparent under low tension as a helicalconfiguration, is similar to that obtained when the strand is treatedunder tension, although usually less marked. Treatment essentiallytension-free has the advantage of eliminating the necessity forcarefully controlling applied tension, as is essential in the tensionedinstance because failure to do so with considerable precision isconducive to undesirable irregularity of helical configuration or crimpin the product.

Heat relaxation of the strand in either instance may be performed byexposure of the cooled strand to an intermediate temperature in heater18, through which it passes at relatively low tension, or may bedeferred until later if desired. The heat-relaxed strand exhibits a moretightly coiled helical configuration, as may be desirable.

The composition of the hot fluid may be selected for reasons of cost,heat-capacity, chemical plasticizing effect upon the strand composition,or other reasons. Gases are preferred because of the tendency of mostliquids to wet the cool roll or the strand or both, which usually isundesirable. Hot air is quite useful accordingly, with'or without theadmixture of steam, for example. Some steam usually is helpful becauseof having a plasticizing effect,

but excessive steam is usually undesirable because of.

problems arising from condensation of water on the apparatus. Combustiongases may be employed, such as acetylene or hydrogen with air or oxygen.Other examples of suitable hot fluids Will occur to persons ordinarilyskilled in the art in the light of the present teaching.

For best results the radius of the cool roll, in centimeters, should notexceed the cube root of the strand preferred maximum roll diameter isabout 20 cm., and for a 15 d. monofilament about 5 cm.

No attempt will be made to list here the considerable variety of strandcompositions subject to successful treatment according to the presentinvention. No reason is known to rule out any plasticizable strandhaving a generally linear polymeric composition and at least partiallymolecularly oriented with respect to the strand axis by predrawing oreven by orientation during its formation by extrusion, for examplerIfdesired, the strand may be oriented during or immediately preparatory tothe jet heating thereof according to the present invention, as by sorelating the speed of the cool roll to exceed thatof the preceding niprolls sufiiciently to impart to the strand.

great enough tension to draw it to increased length, as compared with alower tension suflicient only to extend it temporarily without exceedingits elastic limits. Cross: linked or three-dimensional polymers, whetherorganic or inorganic also may be suitable. One or more additional rollsmay 'be added, in contact with the cool roll or between it and the niprolls to preclude slippage for the purpose of ensuring or drawing simplyas a precautionary measure.

Although a preferred embodiment of this invention has been describedabove and illustrated in conjunction therewith, the above suggested orother modifications therein, as by adding, combining, or subdividingparts or steps, may be made while retaining all or some of the benefitsof the invention, which is defined in the following claims.

The claimed invention:

1. In treatment of a running textile strand wherein the strand is heatedon one side and is maintained relatively cool on the opposite side, theimprovement comprising subjecting the strand on that first side duringthe heating thereof to a stream of hot fluid incident onto the strand atan oblique angle and having a velocity component in the runningdirection greater than the strand velocity.

2. The process of claim 1 wherein the hot fluid is superheated steam.

3. The process of claim 1 wherein the running strand is maintainedrelatively cool on its opposite side by essentially non-slipping contactwith a moving solid surface maintained at a temperature lower than thetemperature of the hot fiuid. 1

4. The process of claim 3 wherein the solid surface is curved and theradius of curvature thereof in centimeters is at most the cube root ofthe strand denier.

5. The process of claim 3 wherein the strand in contact with the solidsurface is substantially tension-free.

-6.' Strand-crimping process comprising forwarding a plasticizablemolecularly oriented textile strand of linear polymeric material into atreating zone, heating the strand on one side only to its plasticizationtemperature by directing thereonto a stream of hot fluid having avelocity component in the forwarding direction, maintaining the oppositeside of the strand cooler than the plasticization temperature andcooling the strand substantially tensionfree, whereupon it assumes acrimped configuration.

7. The process of claim 6 wherein the crimped strand is subsequentlyheated substantially uniformly under tension insuflicient to straightenout the crimp.

8. The process of claim 6 wherein the hot stream of v gas incident onthe one side of the strand disorients and extends the strand on thatside relative to the opposite side.

References Cited UNITED STATES PATENTS 907,823 10/ 1962 Great Britain.

LOUIS K. RIMRODT, Primary Examiner.

12/1963 Taylor 2s 1 UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3,374,514 March 26 1968 Charles A. McClure It iscertified that error appears in the above identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 24, "surface" should read contact Signed and sealed this12th day of August 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, JR.

